Raphael josia



UNTTED STATES PATENT Grates.

RAPHAEL JOSIA, OF FLORENCE, ITALY, ASSIGNOR TO \VILLIAM REY AND C. DE VARIGNY, BOTH OF PARIS, FRANCE.

COMPOSITION FOR TREATING SULPHATES OF LIME FOR THE MANUFACTURE OF ARTIFICIAL MARBLE.

SPECIFICATION forming part of Letters Patent No. 265,506, dated October 3, 1882,

Application filed August 9,1882. (No specimens.)

To all whom it may concern:

Beit known that I, RAPHAEL JosIA, ofFlorence, Kingdom of Italy, have invented or discovered a new and useful Improvement in Compositions for Treating Sulphates of Lime for the Manufacture of Artificial Marble; and I do hereby declare the following to be a full, clear, concise, and exact description thereof.

In an application for Letters Patent of the United States filed March 2, 1882, I have described and made claim to an improved process of treating or preparing gypsum (calcic sulphate or sulphate of lime) in the making of articles of a material which I have termed certaldite without pulverizntion of the gypsum. In said application I described briefly certain ofthe compounds or compositions which I employ to produce certain effects and the manner of using them, but stated that separate applications would be made for patents for such compositions.

The present application relates to one of the compositions so referred to, and it is designed for use in the process herein described in the making of certaldite having yellow spots on a background or body of a general red tint.

In carrying out the process referred to a suitable piece of gypsum (calcic sulphate) is first formed into the desired shape, or approximately such, by the use of suitable well-known tools. lhe gypsum employed may be the ordinary native gypsum of commerce, though I prefer that which is more or less mottled in appearance, having spots of different shades of color. Such gypsum is usually obtained by drated, or containing a certain percentage of water in its composition and the second step in the operation has reference to depriving the gypsum under treatmentof a considerable part or the whole of such water. This is done by subjecting it to the action of a gradually-increasing heat varying by preference, with the size and quantity of the material from 260 to 300 Fahrenheit, for about twelve hours, or until the desired partial or complete dehydration is obtained. The length of time as well as the degree of heat required to effect this result will vary somewhat with the size, character, and purity of the gypsum employed; but the temperature should not exceed 500 Fahrenheit, and both it and the time of exposure should be regulated and limited with reference to securing uniformity of treatment throughout the whole mass or body. This operation may be known to be complete when a fracture ofa test block presents a uniform white color. Any suitable d ying or baking apparatus may be employed for this purpose, manysuch being known in kindred branches of the arts; but it should be of such construction that the material under treatment shall not be brought into direct contact: with the fire. \Vhen the desired dehydration has been eifected the furnace is allowed to cool gradually, in order that the material under treatment may be cooled gradually; or the material may be removed with due care to prevent breaking and exposure to moisture and allowed to cool outside the furnace graduallyuntil itis reduced in temperature sufliciently to permit handling with safety in its subsequent treatment, which is designed to impart to it the desired color or tint and a high degree of insolubility and hardness throughout its mass. This step involves the use ofthe composition which forms the subject-matter of invention in the present application.

This composition is formed of the following elements: water, by weight,two hundred parts; alum, by weight, four to five parts; oxalic acid, by weight, two to two and a half parts; Brazil wood, by weight, six parts; chloride ofzinc, by weight, one part; cream-tartar, by weight, twotenths part; sulphuric acid, by weight, fivetenths part. These ingredients, being mixed in about the proportions named, form a solution which is used as a bath, and to this end a suitable quantity of it is placed in a vessel of proper shape to receive the article to be treated. which is dipped or immersed in the bath and 90 subjected to its action until the article has acquired the desired degree of hardness and color. Thelength of time required to effect this result will depend somewhat on the strength of the ingredients composing the bath or so- 95 lution, the porosity and nature or physical and chemical condition of the article; but usually twelve hours (more or less) will suffice, though to secure uniformity of treatment and of result through the whole body or mass of 10c the article I prefer repeated dippings-two, three, or moresay two or three seconds at first, and increasing gradually to one, two, three, or more minutes, more or less, with drying intervals of like increasing length between dippings for half or three-quarters of an hour or so, after which the article may remain in the bath for twelve hours or so.

\Vhile I do not limit my invention by any particular theory of chemical or physical reactions involved in the use of this bath as above described, I believe, with my present knowledge, that the salt (alum) held in solution, by taking the place of the molecules of water displaced by the previous dehydrating operation, acts chemically or physically upon the calcic sulphate and renders it more compact, harder, and less soluble, and that the oxalic acid of the bath acts chemically or physically upon the impurities or matters of other composition, (carbonates, &c.,) which are usually contained in greater or less quantities in native gypsums, and produces a like indurating effect upon them, though the alum may have an indurating action upon the impurities present, and the acid may act in like manner more or less upon the calcic sulphate. The Brazil wood, creamtartar, and sulphuric acid of the bath act principally as coloring agents to give the desired colors-yellow spots on a reddish ground-and the chloride of zinc acts as a mordant. These colors will usually be variegated somewhat by lines, veins, or markings of darker shades, due probably to impurities present in the calcic sulphate, thus giving the article a beautiful and highly-ornamental appearance. A degree of hardness, compactness, insolubility, and susceptibility of polish is also secured by the use of this bath, which renders the article (certaldite) an excellent and valuable substitute for marbles, ornamental stones, tiles, &c.,i the various uses to which they are applied in the arts.

\Vhen the article has been treated in the bath as above described it is removed and dried by exposure to the sun or to an equivalent furnace-heat for one or two hours, or by ordinary atmospheric exposure for two or three days, when it is ready for polishing and such other manipulations as may best tit it for its intended use, which may he done by any of the methods practiced in kindred arts.

No claim is made herein to the process set forth, as that, with various modifications of the same, as circumstances may require, forms the subject-matter of the first application herein referred to. Neither do I limit my present invention to the particular way herein described of applying it, though I now believe this way or process to he the best. I also believe the proportions ot'ingredien ts which I have named in forming my improved composition to be the best for the purposes stated, and, amongothers, to secure a uniform degree of hardness and color throughout the mass of the article. If the sol ution be very strong, there is great danger of rendering the surface of the article hard very quickly, and thereby preventing proper action of thebath upon the interior substance of the article; or if the solution be "ery weak too much time is required, and even then a proper degree of hardness, density, and insolnbility is not secured; also, by the conjoint action of all the elements of the bath much bet ter results are secured, especially upon native gypsums, than by a solution formed of a part of the elements. For these reasops I prefer to employ all the elements of the c." Jposition in substantially the proportions named; but such limits, though affording the best results, may be varied or exceeded somewhat and still obtain favorable results under skillful manipulation, and all such modifications employing the elements substantially as herein described and in about the proportions set forth I consider as coming within my invention and claim.

I claim as my invention The composition herein described for treating dehydrated gypsum, consisting substantially of the following elements: water, alum, oxalic acid, Brazil wood, chloride ofzinc,crea mtartar, and sulphuric acid, in about the proportions set forth.

In testimony whcreot'I have hereunto set my hand.

GUIDo PANTALIONY, R. H. WI-Irr'rLnsEY. 

